The present invention relates to a method and a device for evaluating a signal from an ion current sensor of an internal combustion engine.
In the related art, a plurality of parameters and states pertaining to the engine, such as combustion detection, combustion start, combustion center, and combustion quality, can be determined from the combustion-chamber pressure. In this context, the combustion-chamber pressure is recorded by a special, suitably mounted pressure sensor.
This method requires an additional bore hole in each cylinder head, as well as a pressure sensor suitable for mass-production.
An ion current soot sensor or an ion current sensor, which is used for the method according to the present invention, is likewise related art for diesel engines. In this context, it is possible to integrate the ion current sensor into the sheathed-element glow plug as well as into the injection nozzle.
From European Patent No. 0190206, a device for measuring and regulating the operating data of internal combustion engines is described, this device including an ion current sensor for specifically detecting pollutant components, such as soot, of an internal combustion engine. Furthermore, additional quantities necessary for the regulation of the internal combustion engine are determined by this ion current sensor.
An object of the present invention is to provide a method and system for measuring and influencing the operating data of an internal combustion engine in order to optimize the combustion process.
The core of the present invention is that a quantity that characterizes a combustion start and/or a quantity that characterizes a combustion quality is determined by conditioning the signal from the ion current sensor.
Due to the strong fluctuations in signal from the ion current sensor, an appropriate signal processing is crucial for extracting the parameters relevant to combustion. In this context, the manner in which the extraction of the parameters is communicated plays a critical role.
An advantage of the present invention is that the stated combustion features are available to the control unit, thereby achieving the desired combustion optimization. In this instance, in contrast to the method which employs a combustion chamber pressure sensor, no additional bore holes are necessary.